1. Field of the Invention
The present invention generally relates to electrical interconnections. More particularly, the present invention relates to sockets.
2. Related Art
While solder is used to form a permanent direct electrical interconnection between components, a socket (also called an interposer in certain applications) is used to form a detachable electrical connection between components (e.g., for processor chip upgrades in computers). Typically, the socket is designed to support a second level electrical interconnection, whereas a first component is electrically coupled to the socket and the socket is electrically coupled to a second component such as a circuit board. Generally, the I/O contact surface of the first component (e.g., a chip package or circuit board) and the I/O contact surface of the second component (e.g., a circuit board, a mother circuit board, etc.) are not planar. Hence, the socket is used to compensate for the non-planarity of these I/O contact surfaces. In particular, the socket has contacts for providing mechanical compliance (i.e., compressibility) and electrical conduction between the first component and the second component. Typically, a compression mechanism provides a compression force for securely maintaining the socket between the first component and the second component.
Although a solid metal is able to transfer electrical signals, its high rigidity prevents its usage in sockets. Thus, different designs for the contacts of the socket have been developed to increase the compliance (i.e., compressibility) of the contacts. These contact designs include a wire button, cantilever springs, pogo pin springs, and an elastomer having metal particles or metal wires embedded inside.
Each of these conventional contact designs is deficient in some manner. For example, some of these conventional contacts are costly to manufacture and are difficult to manufacture. Moreover, other conventional contacts require a large compression force to maintain an electrical connection with the first and second components. Yet still, some conventional contacts wipe or slide on the I/O pads of the first and second components to such a degree to cause extensive wear to the gold plating of the I/O pads. In other cases, the failure mechanism of these conventional contact designs is not well known.
A socket and methods of manufacturing the socket are disclosed. The socket facilitates electrical interconnection. In an embodiment, the socket includes an insulating substrate having a first surface and a second surface that is on an opposite side relative to the first surface. The insulating substrate includes a plurality of apertures each aperture providing a passage between the first and second surfaces. Moreover, the socket includes a plurality of conductive contacts. Each conductive contact is positioned in a respective one of the apertures such that a first end of the conductive contact extends from the first surface and a second end of the conductive contact extends from the second surface. Additionally, each conductive contact is comprised of a foam metal. Alternatively, each conductive contact is comprised of a foam metal and an elastomer.